A few months back I decided to deviate from the BMW recommended TWS motor oil and OEM transmission fluid. My car is an 08 with 40k miles on the clock and tracked 5-6 times a summer. I change my oil at double the recommended interval, and I believe my trans fluid change was the first since the 1200 mile change.

Using TWS, I would burn a litre of oil every 3 track days. After 3 track days using my Redline blend (8 quarts 10W60 with one quart of 5W40), the car hasn't registered any oil loss. I blended the two grades in an attempt to match the 100C kinematic viscosity of TWS, as the redline is a bit thicker. I'll do a blackstone analysis of the redline when I drain it. FWIW, I have noticed absolutely no change in mileage after switching oil (a good sign IMO).

As far as the transmission is concerned, I went to Redline D4 fluid. Initially, i noticed no difference in shifting compared to the fluid I pulled out. A couple track days and a thousand miles and the transmission now shifts a bit smoother.

For anybody considering Redline, I've noticed no noticeable drawbacks of using the fluids.

Used the 10W-60 and seemed fine, though in retrospect should probably be using something thinner after all the interesting comments (the credible ones that is) from earlier posts. What do you guys think of using Redline 5w-50?

Used the 10W-60 and seemed fine, though in retrospect should probably be using something thinner after all the interesting comments (the credible ones that is) from earlier posts. What do you guys think of using Redline 5w-50?

I think, after reading as well, the thinner oil would only benefit the rod bearings, and that's just a theory. As to the other areas of the engine, designed for 10w-60, like the hydraulic lifter assemblies, who knows the effect of thinner weight on those critical areas.

TWS thins down after driving a while. Redline seems to hold its weight better. Mixing in 1 quart of lower weight oil with Redline 10W60 seems like a good idea to get closer to TWS.

Someone should send in a sample of virgin redline 5W50 and 10W60 to see how the SUS Viscosity @ 212*F compares to TWS.

IMO if the 5W50 has a similar viscosity @ operating temp, then the benefit of the lighter base weight for cold starts and flow would just be huge positive. radiatorjoe? uses a blend of redline 40W and 5W30 with great blackstone reports but it's quite a bit lower SUS V than TWS. (68-73 vs. TWS's ~87).

Red Line 10w60 is already thicker than TWS and is more shear stable, meaning that you're running something HEAVIER than stock. You need to ignore the kinematic viscosity values and focus more on the oils' HTHS value as it is more indicative of the operational viscosity.

TWS has a virgin HTHS of around 5.2 and shears to around 4.5ish, then holds steady for the remainder of the change interval. Red Line 10w60 has a virgin of HTHS of 5.8 and probably only shears to the mid- or low-5s over its service life.

That means the Red Line is some 15% heavier than the already-heavy TWS. Personally, I would've just run the Red Line 5w40 (HTHS 4.4) -- it's basically the same weight in-operation as TWS.